(1) Field of the Invention
The present invention is a tier sheet dispensing apparatus for a conveyor system. In particular, the present invention is directed to a tier sheet dispensing apparatus that stores a stack of tier sheets and sequentially dispenses the tier sheets, one at a time, onto the top of a two-dimensionally arrayed layer of objects that is being conveyed on a conveyor system.
The tier sheet dispensing apparatus has a curved surface that supports the stack of tier sheets. The curved surface bends the stack of tier sheets in a convex curve that facilitates the removal of a single sheet from the top of the stack.
The apparatus also has a lift mechanism that moves vertically over the stack of tier sheets to selectively attach to the top tier sheet in the stack and raise the top tier sheet from the stack. The lift mechanism also moves transversely relative to the stack of tier sheets to position the attached tier sheet over the conveyor for placement of the tier sheet on the layer of objects conveyed by the conveyor.
(2) Description of the Related Art
In shipping objects such as cans or plastic bottles, it is cost efficient to stack and secure two-dimensionally arrayed layers of the objects on a pallet. This enables a large number of the objects to be easily transported from one location to another by moving the pallet. The objects are arranged in layers stacked on the pallet, with each layer of objects being separated by a tier sheet. The tier sheets help maintain the positions of the objects in each layer. The layers of objects and the tier sheets positioned between the layers are secured on the pallet by banding, being wrapped by shrink wrap, or other equivalent means.
Conveyor systems are used to transport two-dimensionally arrayed layers of objects to a palletizer where each layer of objects is sequentially stacked on a pallet. A tier sheet dispenser is typically positioned along the conveyor system or at the palletizer to position a tier sheet on top of each layer of objects conveyed past the dispenser.
The typical tier sheet is constructed as a flat, thin rectangular sheet of a material such as fiber board. Just as a pallet is often reused many times in transporting goods, tier sheets are also often used many times in their useful lives. During the life of a typical tier sheet, the edges and the corners of the sheet will become damaged by repeated contacts with other objects, and by the forces exerted by banding or packaging wrap on the edges and the corners of the tier sheet. Due to this damage, only the central portion of the tier sheet remains substantially flat. The damaged edges and the corners will present generally angled surfaces relative to the relatively flat surface of the tier sheet central portion. This presents problems when a plurality of objects are stacked in a two-dimensional array on the tier sheet. The generally flat central portion of the used tier sheet will support the array of objects in their relative positions to each other. However, the damaged edges and corners of the tier sheet often have surfaces that cannot maintain the relative positions of the plurality of objects around the perimeter of the two-dimensionally arrayed stack of objects. This can result in objects falling off of the damaged edges and corners of the tier sheet.
In conveyor systems that are used in conveying two-dimensionally arrayed layers of objects to a palletizer, the quicker the conveyor system can move the layers of objects to the palletizer to load the layer of objects on a pallet, the more cost efficiently the conveyor system and palletizer can be operated. One of the more time consuming steps in conveying a layer of objects to a pallet to be palletized is in the positioning of a tier sheet on the layer of objects and in the stacking of the layer of objects on another layer of objects and a tier sheet that have been previously stacked on a pallet. This is particularly true if objects from the arrayed layer of objects positioned on a tier sheet fall from the perimeter of the arrayed layer of objects due to the damaged edges and corners of the tier sheet. If the time involved in positioning a tier sheet on a layer of objects can be reduced, and if the objects of a subsequent layer of objects positioned on the tier sheet could be prevented from falling from the edges and corners of a used tier sheet, then the time involved in loading a pallet can be appreciably reduced. This can result in a significant reduction in the costs involved in palletizing objects for transportation.